docs: def ls_cmd(argv):
      """List available environments."""
      parser = argparse.ArgumentParser()
      p_group = parser.add_mutually_exclusive_group()
      p_group.add_argument('-b', '--brief', action='store_false')
      p_group.add_argument('-l', '--long', action='store_true')
      args = parser.parse_args(argv)
      lsvirtualenv(args.long)